Yoshimura AT2 full exhaust installation question

[Marinegordon]

Good evening everyone first post here but i've been lurking!


Question: I bought a full yoshi at2 exhaust for my gen 3 busa, I had the dealer install because I wanted it done professionally and I know I would somehow make a mistake. I just got to 600 miles for my break in and I removed the lower fairing to do my oil change/filter and I wanted to inspect the exhaust this is what I saw in pics included.

my question is, are the headers and the clamps not supposed to be all the way tightened or are they designed like that on purpose? If anyone with a better eye for this can take a look and tell me if that looks normal to yall, I have never installed an exhaust so frankly it just looked weird to me and I wanted to confirm or deny.

 

[dcnblues]

Pretty sure that's normal. It's a leverage / temperature thing and yes it is designed that way. You might also see those flanges bend in with a few miles on the bike. However, there are crush gaskets left in the port when you take the stock system off. And they need to be pried out of there before installing the new system. The Yoshimura system doesn't use them, so if I were you I would ask the service guys to confirm that they got them out. If you develop a leak, don't worry, you'll hear it.

ps there's also a misconception that's fairly common for the oil drain bolt crusher. It's a good idea to replace that crush washer with oil changes, and when you do the flat side goes against the bolt so that the round side can crush against the engine case and provide a better seal. I'm like 90% sure I got that right.

 

[Dai.]

That’s normal even on the Akrapovic full system.

 

[Marinegordon]

Pretty sure that's normal. It's a leverage / temperature thing and yes it is designed that way. You might also see those flanges bend in with a few miles on the bike. However, there are crush gaskets left in the port when you take the stock system off. And they need to be pried out of there before installing the new system. The Yoshimura system doesn't use them, so if I were you I would ask the service guys to confirm that they got them out. If you develop a leak, don't worry, you'll hear it.

ps there's also a misconception that's fairly common for the oil drain bolt crusher. It's a good idea to replace that crush washer with oil changes, and when you do the flat side goes against the bolt so that the round side can crush against the engine case and provide a better seal. I'm like 90% sure I got that right.

ahh ok thank you for the reply! I didnt end up doing the oil change because i couldn't find the right crush washer so im heading to the dealer tomorrow to see if they have one and then order online for future changes. I was worried about the crush gaskets left inside thats why I posted this initially i thought maybe they stuck out too far but if yall say its normal its probably ok since they have installed a lot of at2 systems lately. I do not hear any exhaust leak from the front so thats a good thing

 

[Marinegordon]

That’s normal even on the Akrapovic full system.

right on thank you!

 

[dcnblues]

The AT2 is loud, isn't it? Also great looking...

I even like that it's not quite as free flowing as the Brocks. Helps keep the torque and Power Band on the left side of the dino sheet. I like it there. I remember putting the power commander on my gen 1 and loading a map for my four into two full system, and having more grunt mid-range. I called it 'sooner power!' I like sooner power!

 

[dadofthree]

You will hear a leak

 

[Armoni76]

Yep, 100% genuine ! Here is the Yoshi diagram and you can see the springs at the top of the header (part #13)

https://docs.yoshimura-rd.com/11211AP520.pdf

 

[Marinegordon]

The AT2 is loud, isn't it? Also great looking...

I even like that it's not quite as free flowing as the Brocks. Helps keep the torque and Power Band on the left side of the dino sheet. I like it there. I remember putting the power commander on my gen 1 and loading a map for my four into two full system, and having more grunt mid-range. I called it 'sooner power!' I like sooner power!

It’s actually really loud I had a agv k6 helmet and it hurt my ears in it. I upgraded to the shoei x15 and it doesn’t hurt anymore although I could have just gone dead lol. I def use the lower end of the rpm’s a lot more and it makes a nice pop when shifting gears.

 

[sixpack577]

It’s actually really loud I had a agv k6 helmet and it hurt my ears in it. I upgraded to the shoei x15 and it doesn’t hurt anymore although I could have just gone dead lol. I def use the lower end of the rpm’s a lot more and it makes a nice pop when shifting gears.

Alot of us ride with earplugs, mainly for wind noise, but helps with loud exhaust too.

 

[Marinegordon]

Alot of us ride with earplugs, mainly for wind noise, but helps with loud exhaust too.

ya i bought a pair of MOTO PRO Earplugs - MAX - 24dB for some future rides haven't tested them yet and not sure if theyre just a gimmick but they got good reviews.

 

[dcnblues]

Find a local audiologist and get impressions made. They'll make a custom mold that goes inside your ear and matches with your earbuds. I was skeptical, but now that I've done it it's pretty fantastic. Maybe a couple of hundred bucks. Mine are not recommended for helmets but I have learned how to hold the helmet padding away with a finger while pulling it on. Once the helmet is on there's plenty of room in there. You may want earbuds with a microphone, I use Shure, and the software blocks outside sound and gives you music from your cell phone, but if you hit pause it will boost ambient noise and you can have perfectly fine conversations with people, then tap the phone and go back to music and no outside sound gets in.

 

[dcnblues]

Alot of us ride with earplugs, mainly for wind noise, but helps with loud exhaust too.

It's pretty mandatory to prevent tinnitus. Rock concerts and driving with the windows open, or God help you in a convertible, and certainly riding motorcycles will f*** up your ears. Hearing a constant high-pitched twine, especially when you're trying to sleep, is no fun.

 

[dcnblues]

Yep, 100% genuine ! Here is the Yoshi diagram and you can see the springs at the top of the header (part #13)

https://docs.yoshimura-rd.com/11211AP520.pdf

I think he was worried about the flange not being flush with the engine port. But the reason they design it with that Gap is to let the pipe cool down ( which it will do even in that short inch or less) and keep the bolts from cooking (I think).
There's also a good preventive maintenance that you can ask whether the shop did or not, and that's putting anti-seize on the bolts before torquing them into the engine block. People have had an unpleasant time trying to get the bolts out after tens of thousands of miles, but mine came out okay after about 9,000. When I put the at2 on my gen 3 though, I did use copper anti-seize. The hard part is doing the research and deciding whether you're going to reduce the torque spec. Which some recommend and some don't. That's a rabbit hole of research and opinion, but I did reduce the torque 10%.

 

[Marinegordon]

I think he was worried about the flange not being flush with the engine port. But the reason they design it with that Gap is to let the pipe cool down ( which it will do even in that short inch or less) and keep the bolts from cooking (I think).
There's also a good preventive maintenance that you can ask whether the shop did or not, and that's putting anti-seize on the bolts before torquing them into the engine block. People have had an unpleasant time trying to get the bolts out after tens of thousands of miles, but mine came out okay after about 9,000. When I put the at2 on my gen 3 though, I did use copper anti-seize. The hard part is doing the research and deciding whether you're going to reduce the torque spec. Which some recommend and some don't. That's a rabbit hole of research and opinion, but I did reduce the torque 10%.

The earplugs i got are similar to what your talking about here or they advertise that they block wind noise and allow for cardo and traffic noises to be audible for safety. I will test this weekend since its suppose to be nice. My ears are already screwed from the marines, shot a 50 cal without earpro once during qrf training and when i tell you i couldnt hear for like 4 hours after man i could not. VA denied claim haha


i bought the correct crush washers only problem is the old crush washer did not want to come off at all so had to order a new oil drain plug its always something.

 

[Procrastinator]

It’s actually really loud I had a agv k6 helmet and it hurt my ears in it. I upgraded to the shoei x15 and it doesn’t hurt anymore although I could have just gone dead lol. I def use the lower end of the rpm’s a lot more and it makes a nice pop when shifting gears.

Out of interest, did you get the ECU flashed as well and corrected/optimised the fueling?

Also what are you initial thoughts compared to the stock exhaust? The bike would clearly be much lighter but is it noticeable?

 

[dcnblues]

It's noticeable.